1. Field of the Invention
The present invention relates to an audio signal record format and the reproducing method and apparatus therefor, wherein a memory chip is used as the recording medium.
2. Discussion of Related Art
In an audio signal processing apparatus such as an optical disk player for recording/reproducing an optical disk (e.g., compact disk) or a cassette player for recording/reproducing magnetic tape (e.g., a digital audio tape or a cassette tape), a memory device is used to reproducing an the audio signal instead of a reproducing circuit (e.g., a deck or pickup device) for magnetic tape or disk, which is usually associated with the conventional recording medium.
Thus far, the limited capacity and high cost of semiconductor memory have presented barriers to the recording of an audio signal in the memory as, e.g., pulse code modulated data. Therefore, to record the audio signal in the memory, the data requires compression for reducing the volume of the coded audio signal. Alternatively, the accompaniment signal and vocal signal, which together make up the audio signal, should be recorded separately in different channels.
That is, the data quantity of accompaniment signal can be significantly reduced using a musical instrument digital interface (MIDI) format. Digitizing only the vocal signal requires a lower amount of data than the data sampling associated with a compact disk. Therefore, large amounts of audio signals can be recorded and/or reproduced using a limited memory capacity.
One multichannel musical instrument/computer system is disclosed in U.S. Pat. No. 5,121,667, wherein a memory of large capacity is connected to a plurality of random access memories, and the respective random access memories are connected to an oscillator bank producing a musical sound from a plurality of sound sources. In the above system, the MIDI device is connected to the musical instrument or system for reproducing and/or recording the musical sound.
An improved digital sound recording apparatus, which shows higher portability, reliability and utility for learning language and music, is disclosed in U.S. Pat. No. 5,056,145. In this apparatus a case and an IC card which can be attached to the case, are provided. Digitized vocal data is recorded in the first memory region of the IC card, and an identification code corresponding to the start address of the vocal data is recorded in the second memory region. A reproducing unit included in the case converts the digitized vocal data recorded in the memory into an analog signal which is then output during the language lesson.